Detailed descriptions of radio communication networks and systems can be found in literature, such as in Technical Specifications published by, e.g., the 3rd Generation Partnership Project (3GPP). 3GPP Long Term Evolution (LTE) is the fourth-generation radio communication technologies standard developed within the 3rd Generation Partnership Project (3GPP) to improve the Universal Mobile Telecommunication System (UMTS) standard to cope with future requirements in terms of improved services such as higher data rates, improved efficiency, and lowered costs. The Universal Terrestrial Radio Access Network (UTRAN) is the radio access network of a UMTS and Evolved UTRAN (E-UTRAN) is the radio access network of an LTE system. In an UTRAN and an E-UTRAN, a user equipment (UE) is wirelessly connected to a Radio Base Station (RBS) commonly referred to as a NodeB (NB) in UMTS, and as an evolved NodeB (eNodeB or eNB) in LTE. An RBS is a general term for a radio network node capable of transmitting radio signals to a UE and receiving signals transmitted by a UE.
In radio communication systems, traffic between UEs and radio network nodes is neither homogenously distributed in the radio cells nor is it constant over time. That is, during certain time periods a certain radio cell may be heavily loaded by traffic whereas neighboring radio cells may have a low, or limited, traffic load. Load balancing, i.e. balancing of traffic load between cells, has therefore been proposed as a way to improve the overall performance of radio communication systems for such inhomogeneous situations. Detailed descriptions of load balancing, e.g. as supported by the 3GPP, can be found in literature such as in the Technical Specification 3GPP TS 36.300 V. 11.4.0, see e.g. section 22.4.1. As is known among persons skilled in the art, there exist different ways of balancing traffic load between cells. With load balancing, the cells having a low traffic load can for example become larger and absorb some of the UEs from overloaded neighboring cells. Although these UEs may be relatively far from the new radio network node that is serving the UEs of the new cell, those UEs can be forced to move, e.g. handover, from the overloaded radio cell to a less loaded radio cell. Consequently and to sum up, load balancing is a means to improve the overall performance in terms of balancing the traffic load between the radio cells. In this regard, it should be appreciated that load balancing is not only preformed when the radio cells are on the same frequency and generally cover different geographical areas. Load balancing can for example also be performed when the radio cells are on different frequencies and, e.g., cover partly overlapping radio cells.
However, although the radio cells are balanced in terms of traffic load, there may be occasions when resource utilization is not optimized, or at least not desirably good. For instance, there may be occasions when the resource utilization in terms of how much radio resources that are required to transmit/receive information bits to/from the UE (e.g., bits per Physical Resource Block (PRB)) is not optimal, or at least not desirably good. Furthermore, if one radio cell has a traffic load that is constantly higher than that of a neighboring cell, the load balancing will generally have the effect that UEs are only moved in one direction. That is, the UEs will generally be moved in the direction from the radio cell with the comparatively higher traffic load to the other radio cell (i.e. the radio cell having the comparatively lower traffic load).